Some basic information about Planar Vs Volumetric defects in NDE

Defect shape is usually classified in two types: volumetric, for which the ratio between height and width is next to unity, and planar, whose width is, indeed, very small with respect to the height.

What are planar defect? Give example

Planar flaws are thin in one dimension but larger in the other two dimensions. Defect Height to Width Ratio above 6 is called as Planar defects. Planar defect example (e.g. cracks, lack of fusion and incomplete penetration)

Comparing based on ratio of Height to Width

 

Planar defects  (Height to Width ratio)    

For Sl no 4: Defect Height in mm

Defect Width in mm

Ratio H/W Defect type

  4 0.5 8 Planar         For Sl no 5: 4 0.3 13.33 Planar

For Planar defects, the width may be very small, with respect to the height.

Generally, When the Ratio of H /W= 6 and above, these type of defects are characterised as planar defects.

What are volumetric defects and Defect Height to Width ratio?

Volumetric flaws can be described by three dimensions or a volume.

Volumetric defect height to width ratio is between 1 to 3.8 (refer graph)

Volumetric defects such as slag entrapment and porosity are all easily detected.

UT is used for 1. It is very good for the detection of planar defects and cracks.

RT is used for1. Good for finding volumetric defects such as slag and porosity.2. There are problems in detecting planar defects and fine cracks if these are normal to the beam.

Various defects Height to Width ratio (H/ W Ratio) shapes

Volumetric defect Heigth to width ratio 1.0 to 3.8 ,Transition 3.8 to6, Planar 6 and above

 Volumetric Vs Planar defects ( Height to Width ratio)  

Sl no 1 to5 Height

Width Ratio Defect type

         Sl no 1: 3 3 1 Volumetric defect         Sl no 2 : 4 1.5 2.66 Volumetric defect         

Sl no : 3 4 1 4Partially Volumetric (or) Planar

Sl no 4: 4 0.5 8 Planar defectSl no: 5 4 0.3 13.33 Planar defect

Reference: http://www.oegfzp.at/fileadmin/papers/28_wcndtfinal00028.pdf

Schematic diagram showing the Volumetric defect Vs Planar Defect ratios

Volumetric flaw classification and NDE detection methods

Volumetric flawsPorosity,Inclusions,Slag,Tungsten &Other,Shrinkage,Holes and voids,Corrosion thinning,Corrosion pitting

NDE Detection methodsVisual (surface),Replica (surface),Liquid penetrant (surface),Magnetic particle (surface and subsurface),Eddy current,Microwave,Ultrasonic,Radiography

Table 2 lists some of the various types of planar flaws, along with appropriate NDE detection methods.

Planar flaw classification and NDE detection methodsPlanar flawsSeams,Lamination,Lack of bonding,Forging or rolling lap,Casting cold shut,Heat treatment cracks,Grinding cracks,Plating cracks,Fatigue cracks,Stress-corrosion cracks,Welding cracks,Lack of fusion,Incomplete penetrationBrazing debondNDE detection methodsVisual,Replication microscopy,MT,Magnetic field, ECT,Microwave,Electric current perturbation,Magabsorption,UT,Acoustic emission,Thermography

Reference: http://www.oegfzp.at/fileadmin/papers/28_wcndtfinal00028.pdfCompiled By LRamachandran